ResultBuilder for a Dictionary in > Swift 5.4

ResultBuilder.swift

//
//  DictionaryBuilder.swift
//
//  From blog of alejandrom: https://alejandromp.com/blog/better-dictionary-literals-with-swift-result-builders/
//

import Foundation

/// Based on https://alejandromp.com/blog/better-dictionary-literals-with-swift-result-builders/
///
/// Run following unit test in a test target to understand its use.
/// ```swift
/// func testBuild() {
///     func make(include: Bool) -> [String: Any] {
///         Dictionary<String, Any> {
///             ["foo": 69]
///             if include {
///                 ["bar": 78]
///             }
///             ["end": "HelloWorld"]
///         }
///     }
///
///     let dictNoBar = make(include: false)
///     XCTAssertEqual(dictNoBar["foo"] as? Int, 69)
///     XCTAssertNil(dictNoBar["bar"])
///     XCTAssertEqual(dictNoBar["end"] as? String, "HelloWorld")
///
///     let dictBar = make(include: true)
///     XCTAssertNotNil(dictBar["bar"])
/// }
/// ```
@resultBuilder
struct DictionaryBuilder<Key: Hashable, Value> {
    static func buildBlock(_ dictionaries: Dictionary<Key, Value>...) -> Dictionary<Key, Value> {
        dictionaries.reduce(into: [:]) {
            $0.merge($1) { _, new in new }
        }
    }
    static func buildOptional(_ dictionary: Dictionary<Key, Value>?) -> Dictionary<Key, Value> {
        dictionary ?? [:]
    }
}

extension Dictionary {
    init(@DictionaryBuilder<Key, Value> build: () -> Dictionary) {
        self = build()
    }
}

Thanks @alexito4 for this nice simple resultbuilder explained in your blog https://alejandromp.com/blog/better-dictionary-literals-with-swift-result-builders/. For future reference for myself I put it in this gist.